Communication systems, such as point-to-point microwave links, often communicate via directional antennas. In order to establish and maintain communication, the directional antennas should be accurately aligned.
Several methods and systems for performing antenna alignment are known in the art. For example, U.S. Pat. No. 6,661,373, whose disclosure is incorporated herein by reference, describes an antenna alignment meter, which comprises a receiver for detecting a signal with predetermined characteristics and outputting data pertaining to the detection of the signal, and a controller responsive to the data from the receiver for controlling generation of an indicator that signal has been received. The meter can be used for aligning an antenna with a signal source. The meter is arranged to monitor signals received by the antenna and to provide an indication of correct alignment of the antenna with a desired signal source when a signal of a predetermined frequency, polarization, symbol rate and error correction is received.
As another example, U.S. Pat. No. 6,611,696, whose disclosure is incorporated herein by reference, describes an apparatus and method for aligning the antennas of two transceivers of a point-to-point wireless millimeter wave communications link. A narrow band oscillator power source is substituted for the signal transmitting electronics associated with a first antenna and a power detector is substituted for the signal receiving electronics associated with a second antenna. After the antennas are aligned the transceiver electronics are reconnected.
U.S. Pat. No. 6,879,295, whose disclosure is incorporated herein by reference, describes a method in which radio antennas are aligned with each other for the creation of a fixed radio link by temporarily mounting a powered actuator on an antenna forming one end of the link. The actuator is arranged to adjust the alignment of the antenna. The movement of the actuator is controlled over a range of alignments, and variations in the properties of a signal transmitted over the link are measured as the actuator is moved. An optimum actuator position is identified, and the actuator is locked in the optimum position. By using a powered antenna, it is possible to control the alignment of several antennas from a single convenient location. Once the antenna has been secured in the selected position the powered actuator may be recovered for use elsewhere
U.S. Pat. No. 6,587,699, whose disclosure is incorporated herein by reference, describes a system and method for aligning the antennas of two transceivers of a point-to-point wireless millimeter wave communications link and keeping them aligned. Each of two communicating antennas is equipped with a telescopic camera connected to a processor programmed to recognize landscape images. The processors are programmed to remember the pattern of the landscape as it appears when the antennas are aligned. Each of the cameras then view the landscape periodically or continuously and if the landscape in view changes by more than a predetermined amount a signal is provided to indicate a misalignment.
Several vendors offer test sets and kits for microwave antenna alignment. For example, Pendulum Instruments, Inc. (Oakland, Calif.), offers an antenna alignment test set called Path Align-R™. Further details regarding this product are available at www.pendulum-instruments.com/eng/htm/xl—2241.php. Another antenna alignment kit is offered by Teletronics, Inc. (Rockville, Md.). Details regarding this product are available at www.teletronics.com/Accessories.html #antennaalignmentkit.